Acid-Base Balance of Hemolymph in Disk Abalone Haliotis (Nordotis) discus discus in Normoxic Conditions

Creators Handa Takeshi

Creators Araki Akira

Creators Yamamoto Ken-ichi

We examined hemolymph pH, total CO_2 content (Tco_2), CO_2 partial pressure (Pco_2), and bicarbonate concentration ([HCO_3^–]) in order to evaluate the acid–base balance of disk abalone Haliotis (Nordotis) discus discus in normoxic conditions. Hemolymph from disk abalone submerged in experimental seawater was collected anaerobically from the vein located near the margin of the shell using a cannula. The mean values of hemolymph pH and Tco_2 were 7.320 and 1.78 mM/L, respectively. The apparent dissociation constant of carbonic acid (pKapp) was estimated using the following equation: pKapp = – 7.322 + 2.367 • pH + 0.176 • pH^2 – 0.0335 • pH^3. Using αco_2 (37.13 μM/L/torr) and pKapp determined in this study, the hemolymph Pco_2 and [HCO_3^–] were calculated as 4.21 torr and 1.63 mM/L, respectively. The non-bicarbonate buffer value was 3.62 Slykes. These hemolymph properties were compared with those of other molluscan species, Pteriidae bivalves. Disk abalone could have a hemolymph acid–base balance that is similar to other Haliotidae, and have higher buffer capacity of non-bicarbonate buffer system than bivalves.

[ISSN]0370-9361